Johnson et al. (2008) did not find evidence to support E. cinereiceps as a separate taxon from E. albocollaris , and that priority should be given to the senior synonym, E. cinereiceps, as the valid name.

Justification:There is a suspected population reduction of ≥80% in this species over a three generation period (24 years, estimating the generation length to be 8 years). This time period includes both the past and the future. Causes of this reduction (which have not ceased) include continuing decline in area, extent and quality of habitat, and exploitation through unsustainable levels of hunting. In 1997 a powerful cyclone reduced coastal populations by about 50%. Furthermore, E. cinereiceps has undergone significant hybridization with E. rufifrons in the northern part of its range (about half of its total distribution), whilst coastal populations have simultaneously suffered a significant genetic bottleneck. Based on these premises, the species is listed as Critically Endangered.

This species occurs only in southeastern Madagascar in a thin strip of tropical moist lowland forest (sea level to 900 m) that runs from the Andringitra Massif south to the Mananara River. Two isolated populations of this species occurs in the Manombo Special Reserve and in Mahabo Forest south of Farafangana; a small coastal plain population may also occur at Vohipaho, south of the Mananara River, although genetic analyses are needed to confirm whether this is E. cinereiceps or E. collaris. Recent analyses of Landsat imagery estimate that total habitat remaining within this species’ range is less than 700 km2 (Irwin et al. 2005). South-east of the Andringitra Massif, there is a 45 km wide hybrid zone between E. rufifrons and E. cinereiceps, centredat the headwaters of the Manampatrana.

Brenneman et al. (2012) report population densities of 8.7-13.5/km2, among the lowest reported for the genus. The hybrid zone at Andringitra maintains very high densities (58/km2; Irwin et al. 2005); however, estimated rates of cross-population migration are low and the hybrid zone appears to be stable, suggesting a relatively low risk of hybridization ‘swamping out’ populations of E. cinereiceps in the interior forests (Delmore et al. 2011, Wyner et al. 2002). Cyclone Gretelle apparently reduced coastal populations in 1997 (Ratsimbazafy et al. 2002), but densities did not differ from pre-cyclone levels by 2007 (Johnson et al. 2011). Total populations for coastal fragments at Agnalazaha (Mahabo) and Manombo are 134 and 605 individuals, respectively (Brenneman et al. 2012). Number of breeding individuals estimated from population genetics is lower for all populations: 13 for Agnalazaha and 30 each for Manombo and the interior, continuous forest of Vevembe (Brenneman et al. 2012). Grey-headed Lemursat coastal forests also demonstrate a higher probability of having undergone a significant population bottleneck within the last 20-500 year (Brenneman et al. 2012). Irwin et al. (2005) estimate a maximum population size for the species of 7,265+/-2,268 individuals.

This species is found in moist lowland and montane forest habitats, as well as littoral forests. It relies primarily on fruit, particularly in coastal areas where they are among the most frugivorous of all lemurs; its diet is supplemented with leaves, flowers, fungi, and insects. (Johnson 2006, Ralainasolo et al. 2008, Ingraldi et al. 2010). Flowers are an especially important food item late in the dry season. The very dense hybrid population at Andringitra rely heavily on strangler figs during this period, so the substantially lower densities of Grey-headed Lemurs may be related to low availability of suitable fallback foods. This species has high fission-fusion dynamics and frequently use forest edges, which may enhance its ecological flexibility. Relatively fast histories may also contribute to its resilience or resistance to environmental changes, such as in the aftermath of cyclones – however, this flexibility may be compromised by increased fragmentation and climate change (Johnson et al. 2011).

E. cinereiceps has among the most restricted distribution of its genus, with recent analyses of satellite imagery estimating that total habitat remaining within its range is little more than 700 km2. In 1997 a powerful cyclone reduced the coastal population by about 50% (Ratsimbazafy et al. 2002). Coastal populations have simultaneously suffered a significant genetic bottleneck (Brenneman et al. 2012). Effective population size (i.e., the number of breeding individuals) falls well below total population estimates. Selective logging, hunting and the continued conversion of rain forest habitat to agricultural land are the greatest threats to the survival of the Grey-headed Lemur. It is trapped easily by hunters during the fruiting season of the strawberry guava (Psidium cattlianum) in Manombo (J. Ratsimbazafy pers. comm.). In the rest of its range it is hunted with shotguns, snares and slingshots particularly when it comes into coffee plantations.

This species is listed on Appendix I of CITES. E. cinereiceps has been listed as one of the world's 25 Most Endangered Primates since 2004 (in 2004 and 2006 under the name E. albocollaris) (Johnson et al. 2009). The principal threats to its survival are habitat loss due to slash-and-burn agriculture and logging, and hunting with snares, shotguns, and slingshots. Apparently, it is easily baited and trapped during the fruiting season of the strawberry guava (Psidium cattlianum). On the coast, the species numbers only in the hundreds. The only protected areas in which it occurs are the Manombo Special Reserve and the nearby Agnalazaha Forest, which is now being managed by the Missouri Botanical Garden. Initial searches of other remaining forests in the Farafangana region do not appear to harbor Grey-headed Lemurs (Johnson et al. 2008). Unfortunately, Manombo and Agnalazaha represent less than 5% of the total remaining habitat within this species' range (Irwin et al. 2005). It also occurs in unprotected continuous corridor forests west of Vondrozo, which could be added to existing parks and reserves (Johnson and Overdorff 1999). Conservation International is presently initiating programs for the management of the Fandriana-Vondrozo forest corridor. This will be critical for the long-term survival of the Grey-headed Lemur, as the vast majority of populations are found within this corridor and few are presently protected. Expansion of the Manombo Special Reserve to include the neighboring classified forest is a high conservation priority, as is preservation of the existing, very interesting hybrid zone at Andringitra National Park and surrounding areas. As of 2009, there were approximately a dozen white-collared brown lemurs reported in four zoological collections (ISIS 2009), but only one of these (Linton Zoo, UK) is keeping a breeding group (C. Schwitzer pers. obs.).